Reverse motion preventing mechanism



Feb. 20, 1962 w. w. PATTERSON III, ET AL 3,021,924

REVERSE MOTION PREVENTING MECHANISM Original Filed Nov. 15, 1957 I I29 I06 mm 05 INVENTORS. William W Paflersomfl Eugene E Grapes THE IR A T TORNE Y5 United States Patent 3,02L924 REVERSE MQTIGN PREVENEING MEQ'JHANESM William W. Patterson H11, Coraopolis, and Eugene F.

Grapes, Irwin, Pan, assignors to W. W. Patterson, (Joinpany, Pittsburgh, Pa, a corporation of Pennsylvania Originai appiication Nov. 15, 1957, $85. No. 696,816. Divided and this appiication Jan. 2, 1959, Ser. No.

16 Claims. (Cl. 188-825) This invention relates to reverse motion preventing mechanisms, and more particularly, a heavy duty mechanism of such character to mechanically lock against and resist excessive loading and at the same time be readily manually releasable at will despite the loading. It is particularly adapted to lock drums of large-size wire cable, for instance, barge connector cable of the type generally as disclosed in our copending application for Letters Patent, Serial No. 696,816, filed November 15, 1957, of which this application is a division.

In certain types of marine tow work, short lengths of cable are commonly used to secure a group of several barges to one another and to a common tow boat provided for the group. The tension in the individual cable connectors runs as high as 15,000 pounds or more in order to make the barges abut solidly without excessively chafing and the required size of wire cable (1" or 1%") necessary for this tension has considerable weight. A winch drum of fairly large size and load capacity must, therefore, be provided for each cable and generally the drums on mechanical hand winches of conventional de- Sign have proved altogether inadequate or sufficiently unsatisfactory that the operation is a diificult one.

The present winch construction largely eliminates the foregoing ditficulty by providing an operator-powered hydraulic system for work of the above type in which the winch drum is initially turned by hand under a minor mechanical advantage merely to take out the cable slack and in which a hand or foot pump that is provided is then operated to build up pressure on the hydraulic system so as to apply a greatly multiplied hydraulic force for turning the drum to its final position exerting maximum pull. A release type control valve of conventional construction is provided in the hydraulic system and is operated for immediate relief of built-up hydraulic pressure in a way to afford quick release of the cable which is highly desirable for safety reasons and otherwise in tow work.

The foregoing quick release lock effective in the hydraulic system is augmented with a novel mechanical lock of the pawl type provided on the winch and enabling the latter to be locked most effectively both hydraulically and mechanically when not operating. On the other hand, for attaining a commensurate degree of effectiveness whilst operating, this winch takes advantage of the 90%. efiiciency characteristic of hydraulic systems and, accounting for friction and other system losses, the present device nevertheless exerts 15,000 pounds of cable tension with a 50-pound operator input thrust which is especially significant compared to strictly mechanical devices such as screw type. winches which, due primarily to their inherent friction, operate at approximately efiici'ency.

To satisfactorily prevent reverse motion with the mechanical lock just noted, this invention provides a pawlengaging wheel affixed to the cable reel and a rugged type of threaded pawl mechanism which cooperates therewith to lock the reel drum without backlash and which for this purpose has unique features of adjustment and disengagement whereby the pawl is brought into an aligned position of solid engagement with a confronting portion on the drum in all positions and at any time can be released under load without difficulty. More specifi-.- cally, the pawl presents a ball nose and is operatively ar-. ranged for interengagement whereby in securedv position the load reaction cams it into the drum with a self-holding action and whereby, as it approaches the released position, the ball nose is actually forced away from the. drum due to an uncamming action from the load.

The camming and uncamming actions just noted and the further details of construction will become more. apparent from the ensuing description of a preferred embodiment of the invention which we show in the accompanying drawing and in which:

FIGURE 1 is an isometric view of a hydraulic winchembodying the present invention;

FIGURES 2 and 3 are section views taken along the. transverse section lines lill and III-4H of the winch of FIGURE 1; and

FIGURE 4 is a fragmentary view which is generally similar to FIGURE 3 but with portions thereof omitted for clarity.

In the drawing, a hydraulic winch ht? having a, cable reel 91 carries a hand pump 92 which is handle operated by means of a pump shaft adaptor plate 94 and a detachable handle (not shown) and which is secured. to a mounting plate 96 bridged between a pair of frame side plates 93 in the winch 90. The pump 92 contains a reservoir from which it delivers hydraulic fluid under pressure through an outlet 180 into a ram inlet pipe 102 (FiGURE 2). A hand operated release valve 104 is included in a by-pass (not shown) interconnecting the, outlet int) and the pump reservoir for the immediate relief of pressure in the pipe 102. The pipe 102, is directly connected to a ram cylinder 165 which extends generally longitudinally of the frame of the hydraulic winch M. The pipe 102 is a permanent, part of the winch but has sufiicient flexibility to accommodate limited tilting movement of the ram cylinder 105 which has affixed thereto a pivot loop 106 carried on a length of heavy bar 108. of circular cross-section fixed between the plates 98.

A ram 110 has an end extension protruding from the cylinder 105 and carrying a pivot loop 112 which is supported with a rotating fit on a transverse crank pin 116 affixed to the lower end of a block shaped rocker arm 118. A transverse reel shaft 119 fits in bearings (not shown) in the side plates 98 and carries a keyed hand wheel 114 for winding the reel 91 by hand. The rocker arm 11% has a transverse bore at the midportion supporting it with a rotating fit on a shaft 119 so as to oscillate independently thereof.

At the upper end the rocker arm 118 carries a dog clutch formed of a pivoted operating handle 120 and a dog pin 122 which is supported with a sliding fit in an opening in the arm 118 and which is operated bythe handle 120 to push the head of the pin into a registering one of a ring of openings 124 formed in one of the flange portions 126 of the reel 91.

A threaded bolt 128 carried by the rocker arm 118 pive ots the handle 12.0 on a fixed axis at its lower end and at the midportion thereof the handle 120 has. a pinand slot. connection 138 to the adjacent end portion of the dog pinv 122. It is noted that the radius of the ring of openings 124 is substantially greater than half the diameter of the reel flange. portion 126 and at this. distance from the shaft 11%, a dog pin of relatively small diameter has sufficient shear strength to be satisfactorily employed to transmit the desired torque into the reel 91.

Prior to locking the cable reel, the operator rotates the hand wheel 114 to draw a coil of cable 129 thereon hand; tight. He thereupon rotates the handle. 120 in the direction of the plane of the wheel 114 as viewed in FIGURE 1, thus driving the head of the dog pin 122 into interenspawns gaged relationship socketed within the adjacent one of the ring of openings 124. Then the operator manually operates the pump 92 causing the ram 110 to extend against the resistance of a precompressed coil return spring 132 located in the cylinder 105. The arm 118 is thereafter oscillated under the hydraulic pressure to a position shown by dotted lines 118a producing the required tension in the cable 129 and normally occuring at a point slightly short of a stop 134 which limits the power stroke of the rocker arm 118. Our novel locking means in the description immediately following is primarily adapted for installations including but not limited to winches of the foregoing type and other types generally as shown in the noted copending application for letters patent.

Locking means is provided for setting the reel 91 in its loaded position, and comprises an assembly of two spaced arms 136 which at the lower end are supported with a rotating fit on the bar 108 for limiting pivoting movement about the latter on a fixed axis. At the upper end the arms 136 are curved on the arc of a circle to wrap against the perihpery of a thick socket wheel structure 138 which is precast integrally with a companion flange portion 141) opposite to the previously noted reel flange portion 126. At the free end, the arms 136 are rigidly secured together by a block shaped pawl holder 141 carried thereby which is longitudinally bored and tapped and in which a screw threaded rod forming a reverse motion preventing pawl 142 is threaded. The pawl 142 is located on the opposite side of the shaft 119 from the bar 108 and at a position preferably slightly spaced from the vertical plane containing the former.

At the external point at which the annular surface of the wheel structure confronts the pawl 142, the pawl is inclined to the normal at that point on the wheel surface to an effective degree making the pawl axis 144 substantially tangent to the periphery of the socket wheel structure 138. The pawl 142 carries a slidable handle 146 by which it is manually rotated under leverage in the axial direction.

At the inner end, the pawl 142 has a ball nose 148 of semi-circular shape adapted to socket itself in a ring of locking depressions formed in the periphery of the wheel structure 138 so as to confront the pawl holder 141. This ring of depressions comprises substantially tangentially extending sockets each having a semi-spherical floor 150 at the inner end and being of a depth at the lowest point which is manifestly less than one full diameter from the nearest point on the socket wheel periphery. More precisely, the socket axes 152 extend diagonally in the direction in which the structure 138 is being urged to rotate due to the strain of the cable 129 on the reel and the axis of the engaged socket substantially coincides with the pawl axis 144 when the latter is fully socketed on the floor 150. By virtue of its diagonal angularity, the inner walls ofeach socket are relatively relieved at one side and the relieved or shallower side is the outermost one relative to the wheel periphery. At this shallow side, the intersection between the interrupted floor of the socket and the adjacent periphery of the socket wheel structure 138 provides a kick-out nose portion 154 over which the ball nose portion 148 on the head of the pawl 142 rides as the latter is tangentially retracted during unlocking.

Although, due to the obliqueness of the straight inner wall of each socket 150, the pawl 142 can inherently ratchet from socket to socket under counter-clockwise rotation of the reel 91 as viewed in FIGURE 3, the pawl 142 is preferably fully retracted to accommodate such unwinding rotation. To reset' the pawl from such retracted position, the operator runs it in axially along its threads to engage the confronting of one of the sockets 150. The thread pitch and the length of handle 146 are selected to provide the proper mechanical leverage ratio to solidly seal the ball nose portion 148 thereof, and the operator continues to turn the handle 146 under that leverage until the pawl is tightly holding the load against backlash.

As viewed in FIGURES 3 and 4, the operator unlocks the pawl 142 by reverse rotation in a manner to make it move rightwardly along the axis 144 enabling load torque on the drum to cause the socket wheel structure 138 to simultaneously undergo rotation in a clockwise sense so' as to follow up the retracting ball nose portion 148. Continued relative movement between the pawl 142 and the engaged socket as they relatively rotate enable them to reach a point at which a reference line R (FIGURE 4) drawn from the pivot axis of the bar 1&8 to their interface of contact will lie normal thereto and at this point, their axes 1M and 152 have diverged to the extent that the ball nose portion 148 occupies substantially a dead center position poised on the cam nose portion 154. Thereafter, the slightest further retractive movement ofthe pawl 142 enables the cam nose portion 154 to wipe therebeneath and cam it off center to an inoperative position outwardly and upwardly about the axis of bar 108 as above indicated; the pawl 142 is preferably rotated 21 further turn or so by hand enabling it to be completely clearof the path of the sockets when the curved arms 136 return to rest upon the wheel structure 138.

At no point does the pawl 142 appreciably bind in its threads or with the walls of the socket as it retracts from center position in that socket past its dead center position on the cam nose and, in fact, the smooth curved wall of the socket floor 150 enables it to ride smoothly as it shifts in relative position. The cross-sectional diameter of the pawl 142 differs sufficiently from that of the socket floor 151 to prevent the binding referred to, the latter being the larger in the range of 5% to 25%, preferably of about 10% larger diameter. it will be appreciated that when the nose portion 148 is centrally socketed in one of the confronting semi-circular floors 150, the cable and drum reaction due to cable tension is such as to wrap the curved ends of the arms 136 and the pawl 142 in their direction of rotation and, therefore, excessive drum reaction merely increases the positiveness of the pawl lock.

In practice, the pump system provided in the winch of the preceding figures is fitted with a conventional safety overload valve (not shown) which is preset at the factory and which functions to release pressure in the cylinder and by-pass the pump at or above a predetermined pressure without attention by the operator. Such overload valve amounts to a built-in means of shock absorption that relieves sudden surges due to barge-to-barge interaction during towing. Its automatic operation assures under ail circumstances that when the maximum pressure desired is reached, the hydraulic system and the other mechanical components will thereafter be prevented from overloading and the cable 129 protected from exceeding the tension allowable within its safety factor.

In operation of the device of the preceding figures, a two-stage method of winching barges together is afforded. First, the cable 129 is hand tightened between the barges by means of the hand wheel 114 to take out slack in the cable; second, the hand clutch lever is operated to couple together the hydraulic ram and the cable reel by means of the rocker arm 113 and the hand pump is then operated for hydraulically driving the cable with maxi; mum pulling action. The usual operational demands on an installation of this character require a total cable travel of approximately 5" to bring the span of cable from hand-tight to the 15,000 pound tension desired to be exerted. In one embodiment of the invention, the hydraulic force amplification factor between the pump handle and the reel 91 was 380:1 and the ram piston diameter was sufficient to successfully give a thrust of approximately 20 tons, although a 30-ton ram is preferred. The designed arm stroke was 7", and when the cable moves the required 5" it then exerts the 15,000 pounds tension corresponding to maximum pulling conditions. After full tension is set the operator pivots the arms 136 and pawl holder to the operating position and tightens the threaded pawl firmly against the aligned tooth of the wheel structure 138.

If desired, the operator can temporarily declutch the connection between the reel 91 and the hydraulic ram and cylinder and then repetitively retract and advance the latter through more power strokes or part strokes to further increase the tension as required. Ordinarily however, the initial power stroke is suifici'ent and then no declutching occurs or is necessary. During sustained operation in which the'tension may stay on for days or weeks, minor hydraulic fluid pressure leakage will not release the tension inasmuch as the mechanical pawl mechanism stays firmly locked. With the pawl mechanism released, however, a simple twist of the knob 104 on the release valve serves as a quick release feature as a safety measure. Otherwise, the thrust loads are adequately taken up in reaction in the hydraulic system due to its positive clutched connection to the reel drum and the contact pressure between the clutch parts holds them firmly in resisting disengagement when under such extreme tension.

As herein disclosed, the declutchable dog-type coupling embodied in the present winch aifords a ready means of exerting substantial winding torque utilizing a short stroke ram. The cable 129 is largely wound-in by hand with the coupling declutched. Clutched engagement of the coupling thereafter prevents unwinding and then the relatively slow progress of the hand-pumped ram takes place in a mere matter of inches. Of course, a clutching action necessitating axial movement of the reel is undesirable in this work because of the cumulative weight of the reel and the cable therearound, and the present clutching parts utilize a sliding motion, but not the reel 91 and reel shaft. Broadly, conventional sliding jaw clutch parts are also contemplated in lieu of the present clutching parts although the latter are preferred.

We have shown a preferred embodiment of the present invention, but it is to be understood that the principles thereof may be otherwise embodied without departing from the spirit of the invention or the scope of the following claims.

We claim:

I. Locking means to releasably lock a rotatable drum member against a load, comprising socket means formed in the periphery of said member with the axis extending diagonally in the direction in which said member is being urged to rotate, a pawl holder pivotally mounted adjacent said drum member and having a fixed pivot point spaced from the center of rotation of said drum member, with the pawl holder disposed in the path of said periphery so as to confront said socket means, locking pawl means threaded through the pawl holder in a position adapted to register with the confronting socket means, said socket and pawl means having portions which present a socket floor and cam nose and a companion ball nose on their respective contacting parts, and also which when in fully socketed position prevent rotation of the drum member under bias of said load and which furthermore, when relatively rotated so the one follows the other, reach a dead center point beyond which the bias of the load forces the cam nose portion to wipe the pawl means away from the engaged socket in a direction out of the path of the periphery of said drum member.

2. Means to releasably lock a rotatable member against a load, comprising socket means formed in the periphery of said member with the axis extending diagonally in the direction in which said member is being urged to rotate, a pawl holder having a mounting which mounts said pawl holder adjacent said drum, said pawl holder having a swing connection to said mounting, with said swing connection spaced with respect to and on one side of the center of rotation of said rotatable member, whereby said pawl holder is disposed in the path of the periphery of said drum member at a point spaced on the opposite side of said center in a manner confronting said socket means, locking pawl means threaded through the pawl. holder so as to register with said confronting socket means, said socket and pawl means having portions which present a socket door and cam nose and a companion ball nose on their respective contacting parts and also which, when fully socketed, present rotation of the drum memher under bias of said load and furthermore which, when relatively rotated so that one follows the other, reach a dead center point beyond which the bias of the load forces the cam nose portion to wipe the pawl means away from the socket in a direction out of the path of the periphery of said rotatable member, the walls of said socket means being relatively relieved at one side only and formed with the cam nose portion at that side.

3. in combination with a wheel element, mean for locking same comprising an elongated pawl, a swinging support therefor, said support carrying mounting means whereby said elongated pawl is mounted for axial movement and for rotation about that axis, said pawl having a locked position seated at an engageable point on said wheel and being retractable therefrom for unlocking said wheel, said mounting means comprising threads in which said pawl turns to coordinate the advancing and retractive movement thereof in response to its axial rotation, said wheel adjacent the aforesaid point thereon being provided with a kick-out cam portion over which the head of the pawl rides as the latter is retracted during unlocking and which immediately beyond the point at which the pawl head is squarely poised thereon causes the pawl to be forced away without further axial rotation.

4. For use with so-cketed annular means adapted to be held fast by a pawl, a one-piece rod-shaped pawl, supporting means with a longitudinal bore therein having threaded engagement with said pawl for supporting it in a confronting relation to a socket on said socketed annular means, the pawl supporting means and longitudinal bore therein establishing said pawl in operative disposition with the axis of the pawl at its point of confrontation with the annular means being inclined to the normal at that point, and means secured to said rod-shaped pawl for applying the torque to operate it in its threads and comprising a slidable handle by which it is manually rotated under leverage.

5. In reverse motion preventing mechanism including a pawl receiving annular socket member to be held fast and pawl mounting means in operative disposition thereadjacent, the combination with said pawl mounting means, of a one-piece pawl threaded through said mounting means so as to protrude at one end therefrom and so that together they each confront said annular socket member at adjacent points, said threads establishing said i pawl inoperative disposition with the axis of the pawl at its point of confrontation with the annular member being inclined to the normal at that point, and handle means for rotating said pawl in its threads in a direction to advance said pawl into said socket means.

6. In combination, a rotatable drum having a diagonally disposed socket formed in the periphery thereof, said socket having a semi-spherically shaped floor which is suihciently shallow that the curved iloor intersects said periphery, a one-piece pawl with a ball-nose formed thereon and with means attached thereto to rotate said pawl, and a pawl holder supporting said pawl in threads effective for rotatably moving the pawl with its ball-nose advancing in an axial direction towards said socket and for reversing said pawl in a retractive direction of movement under reverse rotation of said pawl, said pawl holder being pivoted, said drum effective to cam away the pivoted pawl holder due to said intersection between the periphery and the socket providing a kick-out cam nose portion over which the ball-nose rides from said socket as the pawl continues to be retracted in its threads in the aforesaid reverse direction.

7. Locking means comprising a rotatable member, a

locking pawl therefor coacting with said rotatable member, said rotatable member having a peripherally dispose-d relieved portion thereon with a central axis oblique to the periphery of said member and provided with a semispherical floor and being of a depth less than one diameter from the nearest point in the periphery of said member, and means supporting said locking pawl for said coaction, said locking pawl having a ball-shaped head and normally supported with its head concentricaiiy socketed in said relieved portion and being of a diameter less than the aforesaid diameter of the semi-spherical floor.

8. Means to lock a rotatable drum comprising a pawl holder having an operative position aligned with a point on the periphery of the drum, a set of spaced, pawl-seating means being carried at said periphery, a locking pawl threaded through the pawl holder so as to be adjustable along the axis of the threads and having a protruding head which in the operative position of the holder is axially advanced into seated engagement with the confronting pawl-seating means, and means to pivot said holder between said operative position and a Withdrawn position in which the head of the threaded pawl is out of the path of said set of pawl-seating means on the drum, the longitudinal axis of said threads when extended to the nearest point of the periphery of said drum establishing an obliqueness of angularity of intersection therewith whereby a substantial component of the axial adjustment aforesaid of said locking pawl accommodates concomitant adjustment in the rotative position of the drum.

9. Means to lock a rotatable loaded ratchet wheel comprising a pawl holder, a locking pawl mounted therein having a longitudinal axis, and swinging arm structure connected at one end for up and down swinging movement with respect thereto, said arm structure extending from said one end, towards the vertical plane containing the axis of rotation of said wheel and into a point of g substantial tangency with said wheel at the opposite 'end portion of said arm, there being means mounting the pawl holder rigidly to said opposite end portion of said arm with'the pawl in a confronting position to said ratchet wheel, the mounting means comprising threads meshed between and carried by said pawl and said pawl holder for axially adjusting the locking pawl toward and away from said ratchet wheel so as to hold the load in balance without backlash, the longitudinal axis of said threads when extended to the nearest point of the periphery of said drum establishing an obliqueness of angularity of intersection therewith whereby a substantial component of the axial adjustment aforesaid of said locking pawl accommodates a concomitant adjustment in the rotative position of the drum.

10. Locking means of claim 9 characterized by a lever handle of a predetermined length which is engageable with and which when applied to said locking pawl to rotate same, exerts a desired mechanical ratio through the pitch advantage of said threads for ciiectuating the balance of .the load as aforesaid.

References Cited in the file of this patent UNITED STATES PATENTS 93,014- tSherman et a1. July 27, 1869 619,985 Niles Feb. 21, 1899 1,370,821 Kane Mar. 8, 1921 2,176,472 Rogers et a1 Oct. 17, 1939 2,530,623 Martin Nov. 21, 1950 2,709,504 Mamo May 31, 1955 FOREIGN PATENTS 922,462 France Feb. 3, 1947 182,621 Great Britain July 13, 1922 339,778 Great Britain Dec. 18, 1930 609,642 Great Britain Oct. 5, 1948 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,021,924 February 20, 1962 William W. Patterson III, et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Column 3 line 8, for "occuring" read occurring line 18, for "limiting" read limited line 21 for "perihper read periphery line 6O after "kick-out" insert cam same column 3 line 71, strike out "of", first occurrence;

column 4, line 72, for "arm" read ram column 6 line 7, for "present" read prevent Signed and sealed this 12th day of June 1962,

SEAL) ttest:

DAVID L. LADD NEST W. SWIDER Commissioner of Patents nesting Officer 

